How does a brachial plexus injury occur?
How does a brachial plexus injury occur?
Brachial plexus injuries can occur as a result of:
- Forceful trauma.
- Tumors.
- Inflammation.
- Injuries at birth.
Forceful trauma that can cause a brachial plexus injury
Damage to the upper part of your brachial plexus often occurs when your shoulder is forced down while your neck is forced up and away from your shoulder.
Damage to the lower part of your brachial nerves is more likely to happen when your arm is suddenly forced above your head.
Examples of trauma that can result in damage to your brachial plexus include:
- High-speed motor vehicle collisions, especially motorcycle collisions.
- Falls
- Direct, blunt blows.
- Collisions in contact sports (these are usually more minor brachial plexus injuries and are called “burners” or “stingers”).
- Penetrating injuries, like a gunshot wound (ballistic trauma) or knife wound.
Tumors that can cause brachial plexus injuries
Tumors can grow in or along your brachial plexus or put pressure on your brachial plexus.
Breast cancer and lung cancer are the most common cancers that involve your brachial plexus.
Lymphoma, melanoma and squamous cell carcinomas arising in your head and neck, and malignant mesotheliomas are some of the tumors that can metastasize (spread) to your axillary (armpit) lymph nodes and affect your brachial plexus.
Inflammation
When your body encounters an offending agent (like viruses, bacteria or toxic chemicals) or suffers an injury, it activates your immune system.
Your immune system sends out its first responders: inflammatory cells and cytokines (substances that stimulate more inflammatory cells).
These cells begin an inflammatory response to trap bacteria and other offending agents or start healing injured tissue. While this inflammatory response is necessary in a lot of cases, sometimes your immune system can send out its first responders for no known reason and attack healthy tissue. Or the inflammatory response to an offending agent can be excessive and damage tissues in your body in the process.
A rare syndrome called Parsonage-Turner Syndrome (brachial neuritis) causes inflammation of the brachial plexus without any obvious shoulder injury. It can begin with severe shoulder or arm pain followed by weakness and numbness.
This syndrome is often misdiagnosed as cervical radiculopathy.
Causes of brachial plexus injuries at birth
Infants can experience brachial plexus injuries due to compression inside their birthing parent’s womb or during a difficult delivery. This injury is called neonatal brachial plexus palsy (NBPP). Injury may be caused by the following situations:
- The infant's head and neck pull toward one side as their shoulders pass through the birth canal.
- Stretching of the infant's shoulders during a head-first delivery.
- Pressure on the baby's raised arms during a breech (feet-first) delivery.